.gototop {
    display: none;
    -webkit-animation: hide 350ms ease-out forwards 1;
    animation: hide 350ms ease-out forwards 1;
    padding: 16px 32px;
    border: 0;
    text-align: center;
    background-color:#D5D6E2;
    color: #494A5F;
    position: fixed;
    bottom: 16px;
    right: 16px;
    -webkit-transition: background-color 100ms ease-in-out;
    transition: background-color 100ms ease-in-out;
}
.gototop > span {
    display: inline-block;
    -webkit-transition: transform 100ms 100ms ease-in-out;
    transition: transform 100ms 100ms ease-in-out;
}
.gototop:hover,
.gototop:focus {
    background-color:#D5D6E2;
}
.gototop:hover > span,
.gototop:focus > span {
    -webkit-transform: translateY(-2px);
    transform: translateY(-2px);
}
.isvisible {
    -webkit-animation: show 1s ease-out forwards 1;  /*1s缓慢过渡*/
    animation: show 1s ease-out forwards 1;
}

@-webkit-keyframes hide{
  0% {
    opacity: 1;
    -webkit-transform:translateY(0);
  }
  25%{
    opacity: .5;
    -webkit-transform: rotate(-3deg) translateY(-40px);
  }
  75%{
    -webkit-transform: rotate(3deg);
  }
  100%{
    opacity: 0;
    -webkit-transform:translateY(100px);
  }
}
@keyframes hide{
  0% {
    opacity: 1;
    transform:translateY(0);
  }
  25%{
    opacity: .5;
    transform: rotate(-3deg) translateY(-40px);
  }
  75%{
    transform: rotate(3deg);
  }
  100%{
    opacity: 0;
    transform:translateY(100px);
  }
}

@-webkit-keyframes show{
  0% {
    -webkit-transform: rotate(0deg);
  }
  25%{
    opacity: .5;
    -webkit-transform: rotate(-3deg) translateY(-40px);
  }
  75%{
    -webkit-transform: rotate(3deg);
  }
  100%{
    opacity: 1;
    -webkit-transform: rotate(0deg);
  }
}

@keyframes show{
  0% {
    transform: rotate(0deg);
  }
  25%{
    opacity: .5;
    transform: rotate(-3deg) translateY(-40px);
  }
  75%{
    transform: rotate(3deg);
  }
  100%{
    opacity: 1;
    transform: rotate(0deg);
  }
}
